What is GEN on Boeing 737? (Generator)

The Generator, also known as GEN and abbreviated as GEN, is an essential component of the Boeing 737-800 aircraft. It plays a crucial role in supplying electrical power to various systems and devices onboard the aircraft. The Generator is responsible for converting mechanical energy into electrical energy, which is then distributed throughout the aircraft to power various equipment and systems such as lighting, avionics, and air conditioning.

Understanding the role and functionality of the Generator is crucial for both aviation enthusiasts and professionals alike. In this article, we will explore the Generator’s importance in the Boeing 737-800, its key features, maintenance requirements, and its impact on the overall performance and safety of the aircraft.

Generator Specifications and Working Principle

The Generator on the Boeing 737-800 is a brushless AC generator, which operates on the principle of electromagnetic induction. It is driven by the aircraft’s engine through a constant-speed drive (CSD) unit, which ensures a consistent rotation speed and voltage output regardless of the engine’s RPM.

The Generator’s working principle involves the rotation of a rotor within a stator. The rotor consists of a field winding, which creates a stationary magnetic field when supplied with direct current. As the rotor spins within the stator, the changing magnetic field induces an alternating current (AC) in the stator windings. This AC current is then converted to direct current (DC) through a diode bridge rectifier, facilitating its use in powering the aircraft’s electrical systems and charging the main battery.

The Generator’s electrical output is regulated by the Integrated Drive Generator (IDG) system, which maintains a stable voltage and frequency. The IDG also provides protection against overvoltage and undervoltage conditions, ensuring the electrical systems receive a constant and reliable power supply.

Generator Maintenance and Inspection

Regular maintenance and inspection of the Generator are vital to ensure its continued reliability and proper functioning. Boeing and regulatory authorities provide detailed guidelines and intervals for Generator maintenance based on usage and time since overhaul.

Some of the key maintenance tasks for the Generator include:

  • Regular visual inspections for signs of wear, damage, or contamination
  • Functional tests to ensure proper voltage and frequency output
  • Replacement of brushes and other wearable components as per manufacturer recommendations
  • Periodic lubrication of bearings and other moving parts
  • Scheduled overhaul and testing at designated intervals

During inspections and overhauls, the Generator is carefully disassembled, cleaned, and subjected to rigorous tests to ensure its compliance with specifications and airworthiness standards. The process includes checks for insulation resistance, bearing wear, magnetic field strength, and other critical parameters. Any deviations or anomalies discovered during the inspection process are promptly addressed and rectified to maintain optimal generator performance.

Impact on Aircraft Performance and Safety

The Generator’s reliability and proper functioning are crucial for the overall performance and safety of the Boeing 737-800 aircraft. A malfunctioning Generator can lead to disruptions in electrical power, affecting essential systems such as flight instruments, navigation equipment, and communication devices. These disruptions can have a severe impact on the aircraft’s ability to operate safely and efficiently.

Proper maintenance and regular inspections of the Generator are, therefore, vital to identify and rectify any potential issues before they develop into critical failures. The generator’s robust design and adherence to stringent maintenance procedures contribute to the Boeing 737-800’s outstanding safety record and ensure a reliable power supply throughout the aircraft’s operational life.

Aviation authorities, such as the Federal Aviation Administration (FAA), regularly monitor and enforce compliance with maintenance and inspection requirements to ensure the continued airworthiness of Boeing 737-800 aircraft generators. These regulations and oversight mechanisms further enhance the overall safety and reliability of the aircraft and its electrical systems.


The Generator, or GEN, is a vital component of the Boeing 737-800 aircraft, providing electrical power to essential systems and devices onboard. Its working principle based on electromagnetic induction and the integrated drive generator (IDG) system ensure a stable and reliable power supply. Regular maintenance and inspections are essential to ensure the Generator’s reliability and compliance with airworthiness standards.

Understanding the role and significance of the Generator in the Boeing 737-800 not only highlights the intricate engineering behind the aircraft’s electrical systems but also emphasizes the importance of meticulous maintenance and inspection procedures in ensuring safe and efficient operations.

For further information and technical details about generators and their role in aviation, you can visit FAA’s Generator Handbook (FAA-H-8083-19).

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